Suspected Benghazi Attacker Discovered Dead

A suspect in the September 2012 attack on the U.S. diplomatic compound in Benghazi, Libya, that killed four Americans including Ambassador Chris Stevens has been found dead, CNN reported, citing a Libyan source it didn't identify and "locals in the town of Marj."

Faraj al-Shibli had been detained by a local militia in Marj in eastern Libya where residents said his body was found on Monday, according to CNN. The cause of death is not yet known.

Al-Shibli, whose name is also spelled Chalabi, had been interviewed by the FBI after he was detained in March 2013. Several members of al-Qaida in the Arabian Peninsula who took part in the attack were later indicted under seal, officials told CNN, although it was not clear if al-Shibli was among them.

Sources told the FBI, however that al-Shibli had been in contact with AQAP and other al-Qaida members in Pakistan, CNN said. AQAP responded after the attack in a statement that it was a revenge killing for the death of senior operative Abu Yahya al-Libi, although the group did not claim responsibility.

Al-Shibli was described by The Washington Post as "by far the most notorious suspect" in the Benghazi ambush, but not its only suspect being sought.

The Benghazi attack's mastermind, Ahmed Abu Khatallah, remains in U.S. custody after being captured by U.S. special operations forces in June. A federal magistrate ordered him held until trial. He has pleaded not guilty to one charge of providing material support to terrorists.

Transcripts of military testimony from nine officers about the attack and the U.S. response were released earlier this month, ABC News reported. More congressional testimony about the incident is planned as investigators determine what happened amid the political fallout that continues to follow the Obama administration, which has given conflicting rationale about its response to the attack.